The present invention relates generally to efficiency adjustments in power supply systems, and more particularly, to adjusting the efficiency of a power supply system according to a load.
A computer system is equipped with a power supply system for converting alternating current (AC) power into direct current (DC) power. In general, the power supply system is categorized according to the maximum output power. For details of the power supply system, refer to IBM System×550 W High Efficiency Platinum AC Power Supply or IBM System×750 W High Efficiency Platinum AC Power Supply.
In practice, the actual output power of the power supply system varies with a load. Moreover, the conversion efficiency of the power supply system varies with the load. In general, the distribution of the conversion efficiencies depends on the design of a conversion circuit in the power supply system. Hence, given the same load, efficiency still varies from conversion circuit to conversion circuit. For further details, refer to U.S. Pat. No. 8,391,036 filed by the applicant of this patent application.
Furthermore, U.S. Pat. No. 8,391,036 teaches maintaining the optimal efficiency regardless of variations in a load and, to this end, discloses a power supply system which includes multiple parallel conversion circuits. The power supply system is characterized in that each conversion circuit exhibits its respective efficiency; hence, the power supply system gives considerations to the present load and accordingly switches to any conversion circuit with preferred efficiency (that is, switches to the appropriate efficiency.) However, the power supply system must include multiple conversion circuits at the expense of production cost and to the detriment of space efficiency. Since the volume of a power supply system is governed by industrial standards, the number of conversion circuits contained in a power supply system is quite limited.